Mica sheet



'F. R. MARCEL MIGA SHEET Feb. 25, 1930.

Filed Aug. 8, 1927 'havin Patented Feb. 25, 1930 UNITED STATES PATENT OFFICE FRANCOIS 3. mean, 01' BROOKLYN, NEW YORK 110A smr Application fled Augult 8, 1987. Serial Io. 211,407.

In employing mica for insulating purposes, as well as in many other uses, it is necessa to bend the sheets or pieces of mica in 0 er to enclose coils of resistance wire and for various other reasons. In many instances in the'electricalj art it is necessary to shape sheets of mica to suit various requirements, but due to the natural stiffness of this material and its brittleness, it is ditficult and tedious to shape it, especially to roll it into small tubes. Furthermore, when rolled into tubes and various other shapes it is necessary to hold or retain the mica in position until it-is confined either'by an outer shell or cement or other enclosing means, and this makes handling of the mica slow and expensive. The object of my invention is to provide a method of rendering the sheets of mica more liable or bendable and the product treated y this method. I have found that sheets of mica may be rendered pliable or easily bendable by passing the sheets between rollers teeth intermeshing with each other where y corrugated parallel lines are formed across the mica. The corrugations may be formed crosswise or lengthwise of the sheets,

according to the manner in which they are to be used or shaped, or strips or sheets may be corrugateddiagonally in order to roll the strips or sheets into helical shape. This'latter 'is especially useful where strips of mica are to be Wound spirally around a long, thin heating'un'it and in similar uses. The method consists, broadly, in treating the mica to form corrugations which permanently render the sheets more pliable and the product consists of sheets or strips of mica which have been corrugated in accordance with this method. In the drawing forming part of this application, U

Figure 1 is a plan view of a simple device or machine for treating mica in accordance with my method,

. Figure 2 is an end view thereof,

Figure 3 is a diagrammatic view showing the action of the rollers on the mica,

Figure 4 is an enlarged detail of a portion ofthe teeth of one of the rollers,

Figure 5 is a perspective view of a sheet gating the mica.

shown such a machine adapted for hand operation although it will be understood that it may be arranged to be operated by means of a motor. The machine shown consists of a bed 1 preferably of metal, on which are bolted the upright standards 2, 3 in spaced, parallel relation at op site ends of the bed, preferably by means 0 the bolts 4 which pass throughapertures in the standard and in the base. These standards are provided with vertical slots 5 which serve as guides for the bearin blocks 6, 7 in which the ends of parallel s afts 8, 9 are journaled. The bearing members are adapted to slide vertically and to. be guided by the side ed es of the slot 5 in the standards, the lower oxes resting bearing blocks 6, 7 in which the ends of parmg blocksf6, 7 are duplicated at o posite si es of the machine and the upper caring block 7 at each side of the machine is pressed downwardly with resistible pressure by means of a coiled spring 10 resting cattle top awing I have wardly bythe spring cap 11 w ich is adjusted in'posltlon by means of the bolt 12 passing through the top member or cap 13 extending across the open upper end of the slot 5. The

shafts 8, 9, as stated above, are arranged arallel to each other and one of them pro ects beyond'one of the standards where it has attached to it a hand crank 14 by means of which the shafts may be revolved.

The members which act upon the mica comprises rollers which may be integral with or attached to the shafts 8, 9. For this purpose I have shown the two rollers 15, 16 arranged parallel to each other and each of thesehas teeth 17 extending longitudinally or parallel to the axis-of each roller; and the teeth of one roller engage between or mesh with the teeth of the opposed roller, similar to the teeth of meshing gears. These preferably rounded. I have shown a shelf or platform on which the mica sheets may be placed in position to be fed between the rollers; and the top surface of this shelf will therefore be substantially in horizontal line with the bight of the two rollers.

In carrying out the invention with a piece of mica of rectangular shape, such as is shown at 21 in figure 5, the sheet is placed on the platform 20 with its leading edge parallel with the bight of the rollers, and the sheet is then moved horizontally toward the rollers until the front edge is taken .between them. The rollers are revolved by turning the hand crank 14 and when the forward edge of the sheet of mica has been engaged by the rollers it will be propelled by them in the manner illustrated in Figure 3;

and as the mica passes between the rollers the meshing teeth form corrugations in it which corrugations are parallel to each other, and in the instance cited these corrugations will extend crosswise of the sheet 21. The rollers will be revolved until the whole sheet has been passed between them and discharged at the opposite side of the. rollers, at which time the whole sheet of mica will have been provided with the corrugations 22.

If it is desired to have the corrugations extend diagonally of the sheet or strip-of mica, the strip is placed upon the platform 20 with its longest side registering with or on the other hand these will eliminate accidental splits or breaks of a more injurious character which often occur when mica which has not been treated by this method is bent into various shapes.

The teeth 17 operatemore efiectively on the mica when the to s 18 are narrow or sharp than if they are lunt or dull.

I believe that I am the first toconceive and to prove the fact that mica can be corrugated and thus rendered permanently more of mica rendered-pliable by having corrugations formed therein.

2. As a new article of manufacture, a blank of mica rendered pliable by having closely arranged, parallel corrugations formed therein.

3. As a new article of manufacture, a blank of mica rendered pliable by having closely arranged, fine corrugations formed therein. Signed at the city, county, and State of New York. the 29th da of July, 1927.

' FRANQ IS R. MABGEL.

gauged along the dotted line 23 which .may.

be a gauge line out in the surface of the platform. As the strip is then advanced to{ ward the rollers one corner of it will be first engaged by the rollers and as the rollers are operated the strip of mica will pass diagonally between them and the corrugations- 24 will be formed diagonally of the strip, as.

- as blanks intending thereby to cover all forms I shown in figure 6. It will be understood that in both Figures. 5 and 6 the sheet is illustrated in its partially completed condition as v in actual practice the corrugations will be continued throughout the entire surface of thesheet or strip. In like manner circular washers and various other forms of mica pieces may be fed through the rollers to receive corrugations similar to the plain sheets shown herein and .Iwillrefer to the articles I of mica which may be treated in accordance with this process.

When the mica has been treated to produce the corrugations as above described there will be a slight cracking of the mica. I

along the tops of the corrugations in many instances but this will not materially affect ion 

